Effect of growth substrate on thermal death of thermophilic bacteria

Abstract

The heat sensitivity of gram-negative, hydrocarbon-utilizing thermophilic bacteria was altered by a change in growth substrate. Thermophilic strains CC-6, BI-1, and LEH-1, grown with acetate or n-heptadecane as the carbon source, had a higher survival rate when incubated 5°C above their maximum growth temperature than cells of the same organism after growth on glucose or glycerol. There was a correlation between the growth substrate, heat resistance, and the ratios of cellular n-hexadecanoic acid/branched hexadecanoic acid and n-heptadecanoic acid/branched heptadecanoic acid. The bacterial cells that were more heat resistant had ratios of straight-chain/branched-chain fatty acids above 1.0, whereas the heat-sensitive cells had ratios below 0.6.

Bacterial diversity changes in response to an altitudinal gradient in arid and semi-arid regions and their effects on crops growth

“…Abiotic stresses resistance of the isolates was measured by screening the resistance to alkaline conditions (pH = 10) (Wiegert et al, 2001), salinity stress (final concentration of 100 mM NaCl) (Gupta et al, 2020), osmotic stress (25% polyethylene glycol Mn6000 PEG) (Vardharajula et al, 2011), and thermal stress (cold stress at 15 • C and heat stress at 60 • C) (Merkel and Perry, 1977;Graumann et al, 1996;Mukhtar et al, 2020). Muller Hinton media was used as the basic growth culture media for all the experiments, and the incubation period was 15 h, and plates were kept under dark conditions.…”

Thermal Inactivation Kinetics of Food‐borne Yeasts

“…Heat destruction tests applied in practice had in common the fact that the death rate coefficient (specific death rate) (k) or the decimal reduction time (D) were determined at different temperatures in several experiments (Lundt, 1951;Wucherpfennig and Franke, 1968;Roth, 1969;Djien et al, 1972;Jacobs et al, 1973;Put et al, 1976;Senhaji and Loncin, 1977;Splittstoesser and Splittstoesser, 1977;Merkel and Perry, 1977;Juven et al, 1978;Rajan et al, 1978;Adams et al, 1989).…”

Genome Sequence of Geobacillus thermoleovorans SGAir0734, Isolated from Singapore Air

“… Geobacillus thermoleovorans is a rod-shaped Gram-positive thermophilic bacterium ( 1 ) classified in the phylum Firmicutes . It was first reported as strain LEH-1 in a study on heat sensitivity of thermophilic bacteria ( 2 ) and later designated Bacillus thermoleovorans ( 3 ). Geobacillus thermoleovorans is found in a variety of environments, including gold mines ( 4 ), sugar refineries ( 5 ), and hot springs ( 6 ).…”